You sure your Blockland folder isn't in "C:\Users\[NAME]\Documents\Blockland"?
If that is the case, could it be your computer is in a foreign language?
My Blockland created his own "my documents" folder because "my documents" is called "mijn documenten" in my language and that wasn't supported.
It can be that it is fixed, it has been a while since I installed BL on my computer.
Normally Blockland is installed in "C:/Program Files/Blockland" and Blockland then makes a folder in your documents when you start it up.
What I would do is uninstall it and reinstall it.